1. Field of the Invention
An aspect of the present invention relates to an image scanner scanning an image recorded on a document, and, more particularly, to a document discharge cassette that allows a speeding up of a scanning operation of both faces of the document, an image scanner having the cassette attached thereto, and a document scanning method to be embodied by the scanner having the document discharge cassette attached thereto.
2. Description of the Related Art
In general, an image scanner is a device that scans an image that is recorded on a document and reproduces the scanned image on another document or a display device. Image scanners may also include a digital copying machine, a facsimile, etc., attached thereto.
FIG. 1 is a cross-sectional view schematically illustrating an embodiment of a conventional image scanner that is able to scan both faces of a document. A conventional image scanner 10 includes an image sensor 25 to scan an image recorded on a document, a document feed cassette 12 to load a stack of documents to be fed, an automatic document feed (ADF) roller 15 to pick individual documents one by one from the top position of the stack of documents loaded in the document feed cassette 12 and to feed the picked up document inside a case, a registration roller 17 to align a tip of the fed document and to correct a misalignment of the document, a first feed roller 19 to transfer the aligned document toward the image sensor 25, a second feed roller 20 to pass the image sensor 25 and to transfer the document of which one face is scanned, a document discharge roller 27 to discharge the document of which an image is scanned, and a document discharge cassette 14 to stack the discharged document.
Further, the image scanner 10 includes a path changer 29 to change a document path to a duplex path 35 so as to allow the image scanner 10 to scan the other face of the document and a duplex roller 22 to transfer the document that is advanced into the duplex path 35.
When a plurality of documents are loaded into the document feed cassette 12 and a continuous image scanning operation of the documents is performed, the scanned documents are discharged into the document discharge cassette 14 in an order that is the reverse of the order the documents were loaded in. The reversal of the loading order between the document feed cassette 12 and the document discharge cassette 14 also occurs when the continuous image scanning operation is applied to both faces of the documents.
Specifically, the first document 1 loaded at the top position of the document feed cassette 12 is turned over and is stacked at the bottom of the document discharge cassette 14 after the image scanning operation. A first face 1-i, i.e., an upward face at the document feed cassette 12 and a second face 1-ii, i.e., a downward face are turned downward and upward, respectively at the document discharge cassette 14. Further, the second document 2 and the third document 3, sequentially loaded under the first document 1, at the document feed cassette 12 are sequentially stacked on the first document 1 at the document discharge cassette 14 after the image scanning operation, and first faces 2-i and 3-i, i.e., an upward face, and second faces 2-ii and 3-ii, i.e., a downward face at the document feed cassette 12, are turned over and become downward faces and upward faces, respectively, at the document discharge cassette 14.
However, according to the image scanning operation of the conventional image scanner, in order to apply the above order as the stacking order of documents to be stacked at the document discharge cassette 14 when scanning both faces of a document each document is made to pass along the duplex path 35 twice and by the image sensor 25 three times. As a result, since each document passes the duplex path 35 and the image sensor 25 one time before a discharging of the document, a pass which is, in fact, not related to image scanning, the scanning speed for both faces of the document is slowed, thereby causing additional electric power consumption. Further, there is a high possibility of a jam because a transfer path of the document is extended.